1. Field of the Invention
The present invention relates to a thin film capacitor device including a thin film capacitor, an interposer, a semiconductor device, and manufacturing methods thereof, and more particularly, relates to a thin film capacitor device having a small adverse influence on another device or the like even when a thin film capacitor is short-circuited due to damage done thereto, an interposer, a semiconductor device, and manufacturing methods thereof.
2. Description of the Related Art
In recent years, in order to prevent malfunction of circuits due to variation in power source voltage, high frequency noises, and the like, a decoupling capacitor has been used.
The decoupling capacitor is generally disposed on a circuit substrate and in the vicinity of a device such as a semiconductor integrated circuit. In addition, it is necessary that the decoupling capacitor be connected to the device with a low inductance.
In order to realize the requirement described above, a thin film capacitor has drawn attention which is formed by a micro-fabrication technique for forming thin films. For example, in a thin film capacitor device including this thin film capacitor, when external terminals are formed of many solder bumps (protruding electrodes) provided at short intervals, and when solder bumps for different electrodes are alternately disposed, the thin film capacitor device can be connected to a semiconductor integrated circuit device with a small inductance in a high frequency region.
In addition, when a thin film capacitor device is mounted onto a circuit substrate, mounting by flip chip bonding using solder bumps can be performed, and hence higher reliability and reduction in cost can also be obtained.
As described above, in recent years, a thin film capacitor device has started to be used as a decoupling capacitor, and in this case, the thin film capacitor device is mounted on a circuit substrate and is disposed in the vicinity of a semiconductor integrated circuit device.
However, in this mounting structure described above, wires provided between the thin film capacitor device and the semiconductor integrated circuit device may cause the increase in inductance. In addition, the increase in inductance caused by drawing the wires may degrade high frequency properties of the decoupling capacitor in some cases.
Accordingly, in order to reduce the inductance, a proposal has been made in which a thin film capacitor is disposed right under a semiconductor integrated circuit device (inside a circuit substrate) to minimize the lengths of wires drawn from a power source line and a ground line of the semiconductor integrated circuit device to the thin film capacitor (for example, see Japanese Unexamined Patent Application Publication No. 4-211191).
In addition, as one application of the above structure, the structure has also been proposed in which an interposer embedded thin film capacitors is provided between a package substrate and a semiconductor integrated circuit device mounted thereon (for example, see Japanese Unexamined Patent Application Publication Nos. 7-176453, 2001-68583, and 2001-35990).
However, since a thin film forming a dielectric layer of the thin film capacitor has a very small thickness, such as approximately 100 nm, the dielectric breakdown is liable to occur, and since a dielectric layer having a perovskite crystal structure causes lattice defects and oxygen defects inside the layer (thin film) under specific conditions, the increase in leak current may occur in some cases. In addition, electron behavior at an electrode interface may also cause the increase in leak current in some cases.
When the problem of the dielectric breakdown as described above occurs, adverse phenomena may occur such that a device connected to the thin film capacitor device malfunctions or is damaged. As a result, by the phenomena described above, the reliability of an entire semiconductor package may be degraded in some cases.
In particular, since the decoupling capacitor is provided between a power source line and a ground line, it is believed that damage caused by the dielectric breakdown of the decoupling capacitor may generate a serious and large influence.